How Butterflies Arrive in East Lothian

In previous posts I have described how Speckled Woods and Wall Browns have arrived in East Lothian over the last few years and then colonised the whole county.

They both worked their way up the east coast from Berwickshire, skirting around the Lammermuir Hills, which run along the south of East Lothian. This seems like an obvious route, taking advantage of the milder climate along the coast and avoiding higher slightly baron hills.

It does appear that the Lammermuir Hills, with a maximum elevation of only 535 metres, is quite a barrier for butterflies as they expand their range.

Speckled Woods were first recorded in East Lothian in 2009 right on the south east corner of East Lothian at Dunglass. A year later Wall Browns were discovered in the same location and both species spread around the coast and have also used river valleys as they have colonised the county.

When Large Skippers were also found at Dunglass in 2014 we all expected them to follow the same route, but we were disappointed not to find them further along the coast over the next few years. Instead, the odd record came in suggesting that they had followed the foothills of the Lammermuirs westwards. This summer they were found in good numbers at Levenhall Links, which is on the extreme west of East Lothian. So, it seems that they chose a completely different route across the county.

Of course, Large Skippers are not easy to spot as they whizz about between flowers and maybe they are under-recorded as a result.

It is interesting, then, that Small Skippers were first recorded in East Lothian between Aberlady and Gullane in 2011. They had been recorded previously in the Borders, but hadn’t been spotted anywhere in East Lothian. Over the years more records came in and we have watched them spread east and west along the coast. There were some early records from some woodland south of Aberlady and also up in the Lammermuir Hills at Linn Dean.

It would appear that these little guys took a completely different route into East Lothian and came over the Lammermuirs via Soutra. It is no coincidence that the two main roads coming north into East Lothian are the A1 which follows the coast and the A68 which comes up over Soutra. The highest point of the A68 at Soutra is 364 metres above sea level, so still a bit of a climb, but the lowest point away from the coast.

Last year we moved to the Yarrow Valley in the Scottish Borders. Our house is between 30 and 40 miles from the coast as the crow (or butterfly) flies, but this short distance makes a surprising difference to the weather. We are at 175 metres above sea level, which isn’t that much, but the elevation and distance from the sea appears to have quite an impact on the weather. I can’t say that it is very noticeable, but the season here is at least three weeks behind what it is in more coastal areas.

It is noticeable in the spring that the Daffodils are at least three weeks later, but even later in the year my Buddleia flower at least three weeks behind those plants in our East Lothian garden, from which I took them as cuttings.

Although the summers appear to be just as hot, if not hotter than on the coast it is interesting that the shorter season means that Speckled Woods and Wall Browns, that are now so common in East Lothian, haven’t made it this far inland. However, the more adventurous Small and Large Skippers have both arrived here. It will be interesting to see what the next few years bring.

Wall Brown, Lasiommata megera

Back in February 2018 I reported on how the Wall Brown had arrived in East Lothian and then continued westward across the county. I am pleased to say that the species has continued to do well and has now been recorded over most of the county.

The map below shows sightings up to 2020 and this year it they have been seen right along the coast to the west.

It is interesting how they have tended to move along the coast both in East Lothian and as they have spread up the country.

I moved about 40 miles south of East Lothian last year, but there are no Wall Browns here. They are very common along the coast, but haven't ventured inland. We certainly have a shorter season here and in the spring I notice that plant are up to three weeks behind those on the coast. Possibly the season is just too short for Wall Browns, but I do live in hope that we will see them here soon.

East Lothian Butterflies 2020

For the last few years I have been coordinating the butterfly records from the Countryside Rangers and volunteers in East Lothian and then sending them in to Butterfly Conservation. 2020 was a very unusual year in more ways than one. The coronavirus, weather and my move to the Scottish Borders all impacted on butterfly recording.

After a reasonably mild, but wet winter the weather was wonderful from March until June. Coupled with the good summer of 2019 this resulted in a few early records, such as Small Coppers being seen on the coast near Dunbar on 7th April, the earliest record in Scotland.

Unfortunately in early June we had some very heavy showers and the wet and cloudy weather persisted for much of the rest of the year. I am sure the poor weather later in the summer impacted on the number of butterflies we saw.

The Covid-19 lockdown came into effect in March, meaning that we were not able to travel, other than for essential reasons. Luckily many of the East Lothian Countryside Volunteers took up the request to record the butterflies that they saw in their gardens or while they were taking their daily exercise.

The transects took a real hit, though, as it wasn't possible for people to travel in order to undertake these surveys. Only the John Muir Country Park transect was walked all season and two other transects were walked from July until September. There are normally nine transects regularly walked in East Lothian.

But, thanks to everyone's efforts we received 1,858 ad hoc records of butterflies in 2020, a bit down on the average of 2,200, but much better than it could have been. The number of butterflies recorded varies year on year, but has averaged about 13,000 over the last few years. In 2020 we only recorded 5007 butterflies. Undoubtedly the lack of transect records has contributed to this, but some species didn't appear to do very well last year, particularly those that we normally see in good numbers after June.

Because of all of the variability in 2020, it would be wrong to directly compare the figures with previous years, but there were still some very interesting results.

The spring populations of Large Whites and Small Whites, appeared to do well, but the summer generations were smaller than we are used to seeing. This appeared to correspond with the weather conditions during each generation. The ever-reliable Green-veined Whites, though, did well throughout the year.

After the bumper numbers of Painted Ladies we saw in 2019, it seemed odd that we had so few records last year. In 2019 we recorded 5,395 Painted Ladies, but in 2020 we only had 18 records. The number that arrive on our shores depends on how well they have done in North Africa and southern Europe earlier in the year, but it is interesting to see the dramatic difference there can be each year. You would imagine that with so many returning from the UK in the autumn of 2019 that there would have been a good stock to start the 2020 season with. Possibly there was limited food available in North Africa, maybe the weather in southern Europe wasn’t so good and, of course, we would normally expect to see large numbers appearing on our shores in July, when the weather was particularly rainy here.

The big story of 2020 was Holly Blues. For the last few years we have received one, or occasionally two, records of a Holly Blue in East Lothian. These records have usually been from a 5 kilometre stretch of the coast, leaving us to suspect that there was an undiscovered colony in a large garden or other secluded location in the area. Then in 2019 two colonies were discovered in the village of Gullane, right in the middle of that area.

In the spring of 2020 we we received records from that same general area, but also from further along the coast and from 5 miles inland. Then in July and August we had several more records from all these areas and a bit further afield. By the time we received the last record on September 6th, 90 Holly Blues had been recorded in East Lothian. It was an amazing expansion in their range and most of the sightings were from places which are regularly checked for butterflies so they would have definitely been seen in previous years if they had been there.

Two Large Skippers were spotted, one inland and one at the coast. I suspect that there are more of them around, but they tend to whizz from flower to flower and are often difficult to spot.

There was a mass arrival of Red Admirals at the end of June, but numbers were lower than expected later in the year. I guess the weather didn’t help, but I noticed that many of the caterpillars in my garden were attacked by parasitic wasps and perished. I wonder if the same happened in East Lothian?

However, Peacocks and Commas also seemed to do less well later in the year, suggesting that it may have been more to do with the weather.

In contrast, Small Tortoiseshells had a really good year, which is good to see. There is quite a lot of national concern because their numbers have been declining over the last few years. Let’s hope this is the start of a renaissance for the species.

I only received one Green Hairstreak record in 2020. The Covid restrictions meant that it wasn't possible to check most of the site where they have previously been recorded, which are all quite remote.

It was great seeing Wall Browns continuing to do well. It is ten years since they were first recorded in East Lothian and they can now be found almost anywhere in the county.

Meadow Browns and Small Heaths both appeared to do very well in 2020 and it was surprising to receive so many records, as they are not what you would consider to be garden butterflies.

I didn't receive any records of Northern Brown Argus in 2020. I am only aware of four colonies and three of those are not in places that people would have been able to visit during lockdown. There is a colony on a coastal golf course, where I only saw one Northern Brown Argus in 2019. I hope that they are still there and just weren't spotted by people walking past.

We had 23 species of butterflies recorded in 2020 in East Lothian, which is fantastic given the restrictions we were all under.

I am very grateful to everyone who contributed records last year. I hope it won't be too long before we are seeing butterflies again in the spring and I really hope that restrictions will have been lifted enough for us to be able to get out and see them.

East Lothian Butterflies 2019 Part 2

Continuing on from my previous post ...

Small Copper, Lycaena phlaeas

The Small Copper started the year very well. The first one was recorded on 17th April and two more were seen the following day. The first generation did very well and the second generation started earlier than normal and was seen in good numbers until the middle of August, when numbers crashed. It seems that the periods of heavy rain knocked numbers down. The last Small Copper was recorded on 20th September, six weeks earlier than last year.

Wall Brown, Lasiommata megera

As with many other species in 2019 the Wall Brown appeared early and the spring generation was larger than we would normally expect. Although the summer generation was larger than the spring generation, it was closer to the average number that we have seen over the last few years.

Holly Blue, Celastrina argiolus

The most exciting news of the year was the discovery of a colony of Holly Blues in Gullane. Every year for the last ten years we have had one or two records of Holly Blues. There had been a colony at Newhailes for a number of years, but I don't think they have been seen there since 2013. The other records had all been in the Gullane to North Berwick area and I always thought there must be a colony hidden in a large garden somewhere in the area. On 20th April a Holly Blue was seen near the coast in Gullane and despite careful searching of the area is wasn't seen again. However, on 3rd August another record came in from outside a garden in the village. Over the next few days several other records from the same area were reported with up to seven individuals being seen there. Nine days later another small colony was found in Gullane about 700 metres away. The last record received was from Archerfield about one and a half kilometres away.

All of these records were from quite public areas, so I doubt they are the location of the original mystery colony. It will be really interesting to see how things develop over the next few years.

Green Hairstreak, Callophrys rubi

The Green Hairstreak is found in a few remote colonies around East Lothian, mostly in the Lammermuir Hills. Because of this we don't get many records. The most easily reached site where they are found is Saltoun Wood, but this colony has suffered a serious decline. There had been a fire there early last year and this year we only recorded three individuals in that area. The three records we received were on 30th April, 15th May and 9th June.

Small Heath, Coenonympha pamphilus

2019 was a good year for Small Heaths. It was notable hat they did particularly well in the summer generation. The first record was on 10th May and they were seen through to the 7th September.

Common Blue, Polyommatus icarus

Common Blue did very well in 2019. The first record was on 24th May and I received almost double the normal number of records. As has been noted with other species, it is the year after a good season that the number of butterflies increases.

Meadow Brown, Maniola jurtina

Meadow Browns also did very well in 2019. I was surprised that we didn’t see more in 2018 when we had such good weather, but I realise that the number we see reflects the weather of the previous year. The first record in 2019 was on 18th June. They had quite a short season, but were seen in greater numbers than in the previous six years.

Ringlet, Aphantpopus hyperantus

The number of Ringlets recorded in 2019 was about average, but they were condensed into a shorter season than normal. The first record was on 18th June and they were initially slow to build up their numbers. However, they peaked in the middle of July and then quickly dropped away, with the last record being on the 15th August.

Small Skipper, Thymelicus sylvestris

The Small Skipper has been increasing in number year on year, since it was first discovered in East Lothian in 2011. The trend continued in 2019 when we received records of 677 skippers, an increase of over 50% on the previous year. The first record was on 22nd June and they were seen in great numbers in July. They are also continuing to extend their range in East Lothian.

Dark Green Fritillary, Argynnis aglaja

Dark Green Fritillaries had an amazing year in 2019 with almost twice the normal number being seen. The first record was on 23rd June and they were recorded until 10th August. Dark Green Fritillaries are mostly found on coastal sites in East Lothian but can also be found in one or two remote valleys in the Lammermuir Hills.

Grayling, Hypparchia semele

Grayling are found in three locations in East Lothian. One of these is very remote cleugh in the Lammermuirs and I didn't receive any records from there this year. The other two sites are at Blindwells and Meadowmill. The Blindwells site is about to be lost to a large housing development, but thankfully the contractors have fenced off the area where the Grayling are found. However, this remains a very small area surrounded by earth moving equipment. Amazingly, on the only occasion anyone was able to visit there, they recorded 13 Graylings flying. A few hundred yards away at Meadowmill Graylings were recorded in much greater numbers than in previous years. The first record was on 26th June and records of over 400 Graylings were received.

Northern Brown Argus, Aricia artaxeres

Northern Brown Argus are only known to exist in four small colonies in East Lothian. They are all quite remote and isolated, so take a bit of dedication to get to. Because of this I only received one record of a Northern Brown Argus on the 20th July. I know they did very well in the Scottish Borders and I have no reason to believe that they wouldn't have done well here, too.

I didn't receive any records for Large Skippers in 2019, but I think they will still be out there along the foothills of the Lammermuirs. Neither did I receive any records of Small Pearl Bordered Fritillaries. They are only known from a couple of sites in East Lothian and we never get records of more than one or two in a good year! Given the prolonged period of great weather earlier in the summer I was surprised that we didn't receive any records of Clouded Yellows or any other unusual migrants.

Once again, I want to send a big thank you to everyone who sent in their records to me last year. The combined efforts of everyone creates a very good picture of how butterflies are doing in East Lothian.

The Fall and Rise of the Wall Brown

While I was delighted to see the arrival of the Wall Brown, Lasiommata megera, in 2010 and its subsequent spread across East Lothian I note that it has declined severely in Southern England. Strangely, it is hanging on around the coast of England, but since the mid-1980s, what was once a very common butterfly has become a rare sight in an area centred around Buckinghamshire and Oxfordshire.

The Wall Brown normally produces two generations of butterflies a year. The first generation emerges in May and June and a second generation occurs in August and September. This species over-winters as a caterpillar.

A study, published in December 2014, The lost generation hypothesis: could climate change drive ectotherms into a developmental trap? By Hans Van Dyck, Dries Bonte, Rik Puls, Karl Gotthard and Dirk Maes looked at the declining number of Wall Browns in Belgium.

Their theory is that due to climate change the season for this butterfly is extending. If the first generation is emerging earlier and the subsequent generation is therefore appearing earlier then there is a potential for a third generation to emerge late in the season. However, there is not enough time for this third generation to breed, or for their eggs to hatch in time to make it through the winter. Presumably, eggs and chrysalises can’t survive frosts. It would be interesting to know if all instars of the caterpillar can survive cold weather.

This theory sounds very plausible to me and it could also help to explain why the Wall Brown is now spreading north into East Lothian. We have certainly been experiencing less severe winter weather here over the last 20 years. Possibly before that our season wasn’t long enough for two complete generations to survive and go on to produce caterpillars before the winter set in. In effect we are now experiencing the sort of weather that was once more common in the Home Counties.

Number of Wall Brown records received over the last five years
2013	2014	2015	2016	2017
54	78	70	129	273

2017 was the best year we have had for Wall Browns. The number of records I have received has increased each year since they were first recorded in East Lothian in 2010. Last year we recorded more than twice as many Wall Browns as we had in 2016. They have now made their way right around the coast and to various inland sites.

They are a very welcome addition to the butterflies of East Lothian.

Some Borders Butterflies

I have been particularly busy this year and the weather hasn't been the best for looking for butterflies. However, I have still managed a few trips down to the Scottish Borders to look for butterflies, some of which we don't get here in East Lothian.

Here are the highlights:

Between sessions of clearing the house and keeping the grass and woodlands in check I managed a quick visit to a valley just above our property in Selkirkshire on the 18th June.

I knew this was a good site for Northern Brown Argus, Aricia artaxerxes, but I have never seen them in such numbers. They are such lovely butterflies and I feel so lucky to have such a great site for them close to where we will be living one day.

I think I will indulge in another picture!!

Another thrill for me was the sight of a small orange butterfly - a Small Pearl Bordered Fritillary, Boloria selene, which flew past me and then disappeared. On my way back down the valley I searched through the vegetation and was delighted to find it again. This time it posed nicely for me in the grass. I had thought I had seen one there in the past, but I wasn't 100% sure, so it was good to get a definite identification.

Six days later I took a friend down to the Berwickshire coast where we hoped to see Small Blues, Cupido minimus. Although numbers were lower than we have seen in the past it was great to see these lovely wee butterflies again.

It was quite worrying to see how dried up their food plant, Kidney Vetch, was, not because of the heat but because of the constant North-East wind coming in from the sea. However, we noticed that next to the railway the Kidney Vetch was doing much better out of the wind.

We met the Borders' butterfly recorder while we were there and he showed us where we would see Large Skippers, Ochlodes sylvanus. Despite the wind we were lucky to spot two or three. Two years ago these found their way into East Lothian, but they haven't been spotted since, possibly because the weather has been so poor.

On our walk back I was pleased to see a Wall Brown, Lasiommata megera. We have these in East Lothian, but I still haven't seen one here this year.

Two days ago on my way back down to Selkirkshire I called into a site near Melrose where I know Scotch Argus, Erebia aethiops, are found. These are a fairly scarce butterfly which are able to fly in dull, wet weather when other species are hiding away. I saw them last year flying in the rain!

They are so difficult to get pictures of, as they are very easily disturbed and when they land they always seem to go low down in the grass. I was pleased to be able to get the picture above and then delighted when I was walking back to the car to see the butterfly below feeding on a Thistle flower.

After lunch I returned to the valley above our property where I saw a lot of Small Skippers, Thymelicus sylvestris. This is another butterfly that I thought I had seen before there, but I hadn't seen it for long enough to be sure. It was great to see them in such numbers.

The Northern Brown Argus were also still flying and I saw a few Dark Green Fritillaries, Argynnis aglaja. 

To add a bit of colour there were also Common Blue, Polyommatus icarus, flying among the multitude of brown butterflies such as Meadow Browns, Ringlet and Small Heaths.

It was great to see so many different butterflies and it is really exciting to think that in a couple of years we will be living in amongst them all!